As the liquid preparations of a sparingly water-soluble acidic drug such as a non-steroidal analgesic or anti-inflammatory drug, suspending syrups are disclosed in JP-A-1-258618 and JP-A-2-286615. These syrups, however, have the problem in stability of their suspended particles with lapse of time. More specifically, these publications report that the commercially available suspending liquid preparations preferably have a particle size of 30-250 .mu.m and that particles with a less size undesirably float and those with a larger size precipitate. However, a suspended substance within the disclosed range of particle size precipitates tightly at the bottom of a vessel and thus it should be redispersed by vigorous shaking just before oral administration. However, this redispersion is extremely difficult and even redispersed, there have arisen the problems of an unpleasant rough feeling in the mouth and agglomeration of the drug in the stomach, thus not exerting sufficient effects.
In order to solve the above problems, there may be proposed a means of pulverizing a drug. However, it has been difficult in the processes using conventional apparatuses such as a homogenizer or the like to set up the conditions such as high concentration and viscosity of the drug or stabilizer, a low-temperature control or the like, and the pulverization to the required particle size was difficult to achieve.
Moreover, many of surface active agents or thickeners may dissolve ibuprofen or the like and selection of these suspension-stabilizing components is significant not only for stability of suspended particles but also for irritating property.
Furthermore, many of sparingly water-soluble acidic drugs may melt at or around a sterilization temperature and there have been presented the problems such as diminished ingestiveness due to change in drug properties by a high-temperature sterilization during the preparation.